Drug Use Linked with Brain Differences in Teens

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Teens who have used drugs even just once in their lives have
brain characteristics that are different from those who have
never used drugs, a new study finds.

In the study, the researchers scanned the brains of 71
Mexican-American 16-year-olds, and asked the teens whether they
had ever used drugs, including cigarettes, alcohol, marijuana
and other drugs. The researchers looked at whether the brain
activity of certain regions was in sync (a measure known as
"functional connectivity"), which suggests that the regions are
talking to one another.

Among teens who'd ever used drugs, a brain region known as the
nucleus accumbens — which is thought to play a role in the
rewarding
feeling that can come with taking drugs — was more in sync
with areas of the brain in the prefrontal cortex, compared to in
teens who'd never used drugs. The prefrontal cortex is involved
in decision making, planning and other behaviors that require
complex thinking.

Because the study was conducted at just one point in time, the
researchers cannot determine the reason for these brain
differences, said study researcher David G. Weissman, a graduate
student at the University of California, Davis Center for Mind
and Brain. It could be that drug exposure is responsible for the
differences. But Weissman said he suspects that these brain
differences existed before drug use, and underlie a tendency to
take risks, which includes using drugs, he said.

Weissman said the level of drug use among the teens in the study
was typical of teens that age — about half had used drugs before,
and they did not use drugs very frequently.

"It's possible, but seems unlikely, that that level of use would
produce significant changes [in the brain], but it's an open
question," Weissman said.

The researchers plan to continue to scan the brains of these
teens over time, and see if there are any changes in the results,
including whether there are changes in teens who start using
drugs.

The new finding "brings up an intriguing idea that there are
differences that we can observe in the brain in the way that it's
connected that relate to whether or not kids are using
substances," said Weissman, who conducted the study with Amanda
Guyer, an associate professor at UC Davis, and colleagues.

Future studies could help researchers gain a better understanding
of what leads teens to use substances or participate in other
risky activities, Weissman said. Such studies may help
researchers understand who is at risk for developing later life
problems because of early
drug use, Weissman said.

The study was funded by the William T. Grant Foundation, an
organization that funds research on youth. It was presented
last month at the meeting of the Association for Psychological
Science in San Francisco, and has not yet been published in a
peer-reviewed journal.